Return-signal device for call-boxes.



No. 663,043. I Patented Dec.'4, I900.

, J, &.|"|. M. ROBINSON.

RETURN SIGNAL DEVICE FOR CALL BOXES. (Application filed Feb. 12, 1900.)(Ila Model.) 4 2 $heats5h oatll J. S. H. M; ROBINSON.

RETURN SIGNAL DEVICE FOR CALL BOXES.

. (Application filed 1m; 12. 1900.

(No Model." 2 Sheets-Sheet 2.

Patented Doc. 4, I900.

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U ITED STATES" A PATENT OFFICE.

JOSEPH S. ROBINSON AND HENRY M. ROBINSON, OF CHICAGO, ILLINOIS.

RETURN-SIGNAL DEVICE FOR CALL-BOXES.

SPECIFICATION formingpart of Letters Patent No, 663.043, dated December1 Anplica tion filed February l2 1900. Serial No. 4,973. \NO model-J Toall whom, it may concern:

Be it known that we, JOSEPH S. ROBIN- SON and HENRY M. ROBINSON,citizens of the United States, and residents of Chicago, in the countyof Cook and State of Illinois, have invented certain new and usefulImprovements in Return Signal Devices for Call- Boxes and SystemsTherefor, of which the following is a full, clear, and exactdescription, 'reference being had to the accompanying drawings.

Heretofore in order to inform the patrons of a call-box system thattheir call has been. received at the central station it has beennecessary for the operator to throwinto the circuit an additionalbattery sufficient to overcome both the resistance of the relay and lineand the resistance of the magnets in the call-boxes, and as it wasnecessary for such a system to be prepared for an emergency when severalcalls would engage the circuit at the same time it was necessary thatthe extra battery should be of sufficient potential to overcome anyresistance that might during its use be thrown into the'said circuit.The use of return signals in call-box systems also required the use ofcomparatively expensive mechanism, and in consequence of this and theexpense of installing and maintaining an extra battery and theunsatisfactory operation of the same return-signal systems of call-boxesare not very numerous.

Our invention relates to comparatively inexpensive improvements tocall-boxes, which, first, dispense with the necessity of an extrabattery in the circuit; second, enable the operator to send the returnsignal over the same wire through which the call wasreceived; third,permit the sending of this return signal without increasing thepotential of the circuit; fourth, do not increase the resistance in thecircuit until after the call has been sent to the receiving-station;fifth, reset the call-box immediately said return signal is sent oranother box in the same system is put into operation; sixth, only theresistance-0f one call-box can be shunted into the circuit at a time;seventh, when the circuit is broken no additional resistance can beadded to the circuit by the operation of any call-box which would affectthe proper Working of the circuit when it is again repaired,

and, eighth, when one or more call-boxes are shunted by two grounds noadditional resistance can be added to the circuit by the operation ofthese shunted boxes which would affect the proper Working of the circuitwhen it is again repaired. This we accomplish by the means hereinafterfully described and as particularly pointed out in the claims.

In the drawings, Figure 1 is a front view of a call-box embodying ourinvention. Fig. 2 is a side view of the same. Fig. 3 is a transversevertical section taken on dotted line 3 3, Fig. 1, looking in thedirection indicated by the arrows. Fig. 4: is a plan view of part of themechanism of a call-box, showing a modified form of our improvements.Fig. 5 is a detail view of the detent of said modification. Fig. 6 is adiagrammatical view of the system of which our call-boxes form a part.Fig. 7 is a diagrammatical view of the call-box.

Our invention does not comprise the clock mechanism A, northe usualcircuit-breaking registering-disk or operated thereby, nor the brush bbearing against its recessed periphery to cause the necessary breaks inthe circuit to indicate the number of the box at the receiving-station.These are well-known features of the call-boxes now in extensive use,and therefore no extended description thereof is herein offered.

The clock mechanism A has the usual actuating-spindle B, which extendsout of the box and has a crank c thereon with which it is operated. Justinside the case of the box the spindle B has an upwardly-projecting armG of suitable length which is adapted to engage the return-bend fof thetransverse stretch of an L-shaped pawl E, which is secured to andprojects from the adjacent free end of a shunt-bar F. This pawl is madeof elastic steel wire, and the transverse stretch thereof extends fromthe shunt-bar to a point on the other side of the vertical plane of thespindle B of the clockwork, and is then-bent forward at right angles toits transverse stretch a short distance, and then extends downwardobliquely past spindle B to a point which when the pawl is in its normalposition would be intersected by the vertical plane extending throughsaid spindle. The lower end of the oblique downward stretch of said pawlis provided -with a circular or other shaped plate E, upon which theletters O. K. or other suitable indicia are impressed, which when thereturn signal is given from the receiving-station to a call willappearback of the usual opening in the face of the case of the box and apprisethe patron of the receipt of his call. The normal position of pawl E isthat in which the plate E on its lower end will be back of the openingin the face of the case. It is moved from this position to that shown indotted lines in Fig. l

of the drawings, however, by the arm G whenever the call-box isoperated. The normal position of arm G is such that it bears backagainst the pawl at a point between the return-bend f thereof and theoutward bend of the same. When, therefore, the spindle Bis turnedthrough the medium of the crank on its outer endand then released, armGwhen returning to its original position engages said return-bend f anddraws said pawl with it for a short distance until the shunt-arm hasbeen moved out of contact with a post 9 and near enough to the core ofmagnets H for the armature I, carried by said shunt-bar, to be attractedand held thereby.

Shunt-bar F is pivoted at its upper end opposite that to which pawl E issecured in suitable manner to the pivotal lugs of the contiguous end ofan L-shaped branch j of the magnet-supporting frame J, and itssaid upperend extends beyond its pivot and has attached thereto the contiguous endof a coil contraction-spring h, the other end of which latter is securedto the branch j ofv frame J in such manner as to keep the lower end ofthe shunt-bar normally in contact directly with post 9 or in contactwith the adjacent the negative binding-post 7r. Thus it will be observedthat there is a normally-closed current passing through the boxsubstantially all the time, except when the circuit is'broken by theoperator at the receiving-station to make the return-signal.

The system in which our improved callboxes L are connected has, as shownin Fig. 6 of the drawings, a main single-wire circuit, consisting of thebattery N, the main wire P, having a series of call-boxes, constructedas hereinbefore described, normally electrically closed to it and havinga relay Q closed thereto. The circuit may be grounded after it leavesthe relay or may have a metallic connection with the negative electrodeof the battery. In either event said circuitis provided with a suitablecircuit-breaker R, with which the operator opens the circuit when hedesires to give the return signal to a call, and thereby drops thesignal to its original position and at the same time resets thelast-operated callbox for its next message. This same result, however,could be accomplished, providing the operator neglected his duty, by theoperation of any other call-boxon the system.

The relay Q is adapted to close a normally open. circuit S, and therebyoperate the registering instrument T connected with said circuit everytimethe brush of a call-box in the main circuit passes over the recessesin the circumference of the registering-disks of the same.

We dov not desire to be confined to the use of a signal-pawl ashereinbefore described, as it is obvious that by the use of themechanism shown in Figs. 4 and 5 a signalingarm similar to that used incall-boxes now in limited use .can be employed in connection with ourimprovements. In this case such binding-post k is similarly passedthrough,

say, the lower right-hand corner of said plate. Post K is connected byan insulated wire 5 with brush 1). From thence the current flows throughthe registering-disk, then through the clockwork to the supporting-plateM, and

from the latter to the magnet-supporting frame J. Following the lines ofthe least resistance the current passes through branch j of frame J andinto the shunt-bar, when in its normal position against post g, and thenflows through said post 9 to the negative bindingpost through aconnecting insulated wire 'n.

When the shunt-bar is moved out of contact with post 9 by reason of theengagement of the pawl by the arm G, the current passes through themagnet-supporting frame J into the magnets H, which are electricallyconnected therewith, and from said magnets the current flows through aninsulated wire 0 to an arm X is loosely pivoted to spindle between arm Gand the case and has the O. K. or other suitable indicia suitablyimpressed on its lower end, and has its upper end 01 extended past itspivot and provided with a longitudinal slot e, that is engaged by theoutwardly-turned end 2 of a spring-wire detent W, that holds saidsignal-arm stationary while the call is being given and then causes saidarm to move until its lower end is out from under the exposure-openingof the case, where it is detained until the receiving-operator gives thereturn signal, whereupon it causes said arm to return to its originalposition back of the said exposure-opening, and thereby inform thepatron of the receipt of his call. This detent W is so constructed thatit makes a lateral detour 3 from its outwardly-extended end 2 and thenextends in a transversedirection to and is connected with the adjacentend portion of a shunt-arm F. At a point approximately back of theextension d of arm X when in its normal position the rearwardmosttransverse stretch of the detent has a short outward return-bend w, andprojecting upward from the spindle in such a vertical plane as to nor-IIO mally bear back against the detent is the arm G. The relativeposition of arm G to the return-bend w of the detent is the same as itis to the return-bend fof the pawl. Thus when the call is operated arm Gduring its return movement comes in contact with return-bend w and drawsthe detent with it for a short distance until the shunt-bar is out ofcontact with the post g and is attached by the mag nets, whereupon theoperation of the circuit is the same as hereinbefore described.

We do not desire to be confined to the exact mechanism hereinbeforedescribed for moving the shunt-arm toward the magnets, because othermechanism put in operation, in the first inslance, by the turning of thespindle might be employed. Any construction which will during or afterthe call has been sent switch the circuit through the magnets, andthrough the medium of such energized magnets prevent the return-signaldevices in the box from operating until the circuit is opened, weconsider as coming within the scope of our invention.

What we claim as new is 1. In an electric call-box, the combination withthe call mechanism, of an electromagnet, an armature therefor normallyheld out of engagement with said magnet, a wire connected to saidarmature havingareturn-bend therein, and a bar sliding upon said wire,ac-

tuated by the call mechanism and arranged to engage the return-bend inthe said wire during its movement to move the armature into engagementwith the poles of the electromagnet.

2. In an electric call-box, the combination with anautomatically-returnable revoluble spindle, and arm projectingtherefrom, of signaling devices which include a transverse stretch ofwire having a suitable return-bend made therein engageable by said arm,a shunt-bar to which said wire is attached at one end, and anormally-demagnetized magnet which is magnetized when said shunt-bar ismoved and holds the same and said signaling devices out of their normalpositions until said circuit is opened.

3. In an electric call-box the combination with anautomatically-returnable revoluble spindle, and arm projectingtherefrom, of a pawl having a horizontal stretch having a suitablereturnbend made therein, and extending downward from said transversestretch a suitable distance and carrying suitable registering indiciathereon, a shunt-bar to which one end of the transverse stretch of saidwire is secured, and a normallysdepolarized magnet which is magnetizedwhen said shunt-bar is moved and holds the same and said signalingdevices out of their normal positions until said circuit is opened.

4. In an electric call-box, the combination with the call mechanism, ofan electromagnet, an armature therefor, an electricallyconnectedstop-post, a spring for normally holding the armature in contact withsaid stop-post, a Wire connected to said armature having a return-bendtherein, and carrying signaling devices on its free end, and meansactuated by the call mechanism for moving said wire to actuate thesignaling devices, and move the armature out of contact with thestop-post and into the field of the electromagnet.

JOSEPH S. ROBINSON. HENRY M. ROBINSON. Witnesses:

M. FRIEL,

FRANK D. THOMASON.

